Warmup for 2/21/01: Probability Exercises
- Suppose that, by keeping track of the relative frequencies
of these occurrences over many daily commutes to work,
you notice that
- you have a 30% chance of finding yourself behind
a bus, and
- you have a 50% chance of having to wait for a
red light.
What is the probability that both of these events
will happen (making for a doubly-frustrating commute)?
What is the chance that at least one of the two things
will occur?
- According to the Information Please Almanac (1991,
p. 815), the relative frequency of male babies born
in the United States is about 0.512. Suppose that a certain
married couple desires to have a girl. Assuming they
run in to no obstructions as they have children,
estimate the probability that their first girl arrives as
the fourth child.
- The ACLU (Briefing
Paper Number 5) alleges that some drug-screening tests yield
“false positives” at least 10% of the time. Suppose
the rate is exactly 10%. If you have 5 “clean”
employees to be tested, what is the probability that at
least one tests positive?
- Freddie (still a 70% free-throw shooter) attempts 5 free-throws.
Let X = # of shots made out of these. Give the probability
distribution of X, and then draw its probability histogram
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